Gliederung

Objective

S100B is released by astrocytes into the extracellular fluid after a variety of brain insults, and CSF and serum S100B levels have been correlated to outcome after traumatic brain injury (TBI). As no data exist about the temporal profile of S100B cerebral levels, and their correlation to serum levels, we examined whether MR spectroscopy (MRS) is capable of depicting cerebral S100B levels after TBI.

Methods

At different time points following lateral fluid percussion or sham injury in male Sprague Dawley rats, blood samples were analysed for S100B using a chemiluminescence immunoassay (LIAISONÂ® SangtecÂ®, ByK-Sangtec Diagnostica, Dietzenbach, Germany). At the same time points, MRS was performed on a 2.35 T magnet (gradient strength 25G/cm; Bruker Instr.) using a water suppressed SE voxel localization technique (5x5x5mm3 voxel, TR/TE 3000/30ms, 256aq). Areas under the resultant peaks (EUC) were manually determined, and normalized to NAA.

Results

S100B serum levels in sham animals were below 0.02 ng/ml. After injury, S100B serum levels increased up to 0.47Â±0.14 ng/ml at 3 hr, subsequently returning to normal levels. In sham animals MRS showed a S100B specific peak at 4.5ppm with a EUC of 0.02. After injury, the EUC increased to 0.30 at 3 hr, and up to 0.92 on day 5 post-injury.

Conclusions

S100B serum levels were increased for only a very short period after injury. On the other hand, MRS demonstrated increased cerebral S100B levels up to day 5 after experimental TBI. While experimental data suggest that S100B is actively released by astrocytes after brain insults, MRS may offer a tool to identify increased cerebral S100B levels in patients after TBI. Further studies are needed to examine the contribution of this cerebral release to recovery after TBI.